The present invention relates to a timing mechanism and more particularly to an intermittent drive means for such mechanism.
Generally speaking, there is provided an intermittent drive means for coupling a cam means to a motor drive means of a timing mechanism, the intermittent drive means comprising a motor output member, and a combination of a geneva drive means coupled to the motor output member, and eccentric drive means coupled to the geneva drive means and engaging the cam means.
Timing mechanisms have long been used in the appliance industry to provide program sequences to appliances such as dishwashers, washers, and dryers. Usually in the operation of such timing mechanisms, the cam means, which opens and closes electrical switches, are rotated in a step by step manner by some sort of intermittent drive mechanism.
One type of intermittent drive mechanism uses an eccentric wherein at least one drive pawl operates off an eccentric to index variable ratchet teeth coupled to the cam means. An eccentric in combination with variable ratchet teeth permits large advances of the cam means when critical timing functions are being performed and small advances when no critical functions are performed.
Another type of intermittent motion used in timing mechanisms includes the use of geneva drive means. The use of this type of motion permits the use of dwell periods when no type of motion is desired.
The present invention contemplates the use of a geneva drive mechanism and an eccentric drive mechanism in combination to provide an intermittent motion consisting of dwell and drive periods. Such a combination provides (as will be hereinafter discussed) greater timing accuracy and also increases the life of the electrical contacts used in the switches of the timing mechanism.